Exhaust head



3. BOL

EXHAUST HEAD Sept. 10, 1929.

Filed Feb. 2. 1924 71 91/15/1544 9 7.551210!04III/r1r/a111,1175/15/1515!!!. 2.111751451111515 Fifi/I515; A I.

Invento -z Cornelia Bol, by ,4?

His Attorney.

Patented Sept. 10, 1929.

UNITED STATES PATENT OFFICE.

, V CORNELIS BOL, OF EINDHOVEN, NETHERLANDS, ASSIGNOR '10 GENERALELECTRIC v COMPANY, A CORPORATION OF NEW YORK.

EXHAUST HEAD.

Application filed February 2, 1924, Serial No. 690,330, and inth'eNetherlands March 9, 1923.

This invention relates to an improved device for holding an exhaust tubeor for providing an air tight seal around it and more particularly it isadapted for making an air tight connection of the exhaust-tube of avessel that is to be exhausted to the vacuumconduit as frequently is thecase when exhausting electric incandescent lamps or electric dischargetubes.

The device according to the invention comprises an elastic or resilienttube clamped means at both ends and a device for pressing the freemiddle part of the elastic tube against the exhaust tube by a fluid or agaseous medium under pressure.

As materials for the elastic tube, rubber, caoutchouc, india-rubber,gutta-percha and the like are particularly adapted.

The elastic tube may be placed within a rigid tubular casing, theelastic tube being at both ends clamped air tight to the rigid casingwhilst a device is provided for feeding and dischargin a fluid orgaseous medium under pressure etween the rigid casing and the middlepart of the elastic tube.

Oneor both ends of the elastic tube may be bent around one of the endsof the rigid casing and clamped to it by means of a metal cap, which isresiliently held in position.

An important feature of the invention is the use of a fluid or gaseousmedium for pressing the free middle part of the elastic tube against theexhaust tube so as to obtain by very simple means a uniform pressure onall sides, which is the chief condition for a good air tight seal. Inmany cases the pressure in a common water-pipe is suflicient for thepurpose of the invention, but the use of comressed air is generally moreadvisable. gince a particularly simple means for expanding the elastictube to release the exhaust tube, after compressing the elastic tube bycompressed air is to make use of a vacuum. To this end it is onlynecessary to connect the space which was first connected to thecompressed air-pipe to cause the elastic tube to grip the exhaust tubetoa vacuum-pipe such as the vacuum-pipe which is always used inincandescent lamp factories.

In the case of the device according tothe tube air tight, to

invention being used for connecting a hollow cylindrical body, forexample an exhaust a vacuum-pipe, the elastic tubeis preferably slidover the end of the vacuum-pipe and a metal casing is slid over theelastictube in such a manner that one end of the latter is clamped airtight between the vacuum-pipe and the metal casing. In the sald case thevacuum-pipe may also be provided with a device for supporting theexhaust-tube. This device is preferably vertically movable andresiliently supported.

The accompanying drawing represents a device according to one embodimentof the invention.

Figure 1 is a vertical section of the device with the elastic tubecompressed to grip the exhaust tube.

Figure 2 is a plan and Fig. 3 is a vertical section of the device withthe elastic tube expanded to release the exhaust tube.

According to the drawing a vertical metal .vacuum tube 2 is fixed to avacuum-pipe 1. A tube 4 of rubber or similar material is slid over theupper end of the metal tube 2 and a tubular metal casing 3 is providedaround the said elastic tube. The lower part of the easing 3 telescopesover the upper part of the tube 2 for gripplng the lower end of therubber tube air tight. At this point the tube 2 and the sleeve 3 arepreferably somewhat tapered which ensures a better seal.

The upper part of the rubber tube 4 is bent at 5 around the upper end ofthe casing 3 and a small collar 6 is slid over this upper part in orderto ensure, also at that point, an air tight seal between the rubber tube4 and the casing 3 This air tight seal is improved by the facthat thecollar 6, which is bent at the upper end is resiliently pulleddownwards. To this end lugs 7 and 8 are fixed to the collar 6, andsprings 9 and 10 a-refastened on one side to these lugs and on the otherside to a rirlgg 11, which is rigidly attached to the metal tu e 2.

It will be clear that by this device the rubber tube 4 is clamped airtight at both ends to the wall of the casing 3, whereas the middle partof the rubber tube can move freely inside and radially of the leeve.

For supporting the exhaust tube of the lamp 14 a yielding support isprovided within the metal tube 2. Said support comprising a rod 16 whichcarries at its upper end a fiattened part 15 and a small ring 20 forminga cup shaped head whilst at its lower end it is provided with a'smallguide block 17. It can move vertically in a small bushing 18 which issomewhat contracted at 19 so as to limit upward movement of the rod 16.The latter is supported by a spiral spring 22, which on one side isfastened to the bushing 18 and on the other side to a small ring 21.

When the lamp with the exhaust tube is placed on the support 15, thespring 22 will be somewhat compressed by the weight ofthe lamp, whichofl'ers the advantage hereinafter described.

The pipe 25 joined to the casing 3 serves for feeding and discharging aliquid under pressure, or compressed air, and if necessary for aconnection to a vacuum pipe.

The operation of the exhaust head will now briefly be described When thelamp 14 with the exhaust tube 28 is placed on the upper end of the rod16, the rubber tube 4 is expanded and is in the position shown in Fig. 1so that the exhaust tube may be introduced without any difficulty. Itwill be clear that at this time there is no vacuum in the pipe 1.

A liquid or gas under pressure, preferably compressed air,'is then fedthrough the pipe 25. The valve 29 is turned into the proper position tofeed the compressed air from the pipe 30. The pressure of the compressedair may amount to several atmospheres. The middle part of the rubbertube 4 is thus pressed radially inward against the exhaust tube, wherebyan air tight seal between the rubber conduit and the exhaust tube isobtained. Then the tube 1 is put into connection with avacuum' pump or avacuum conduit and the lamp 14 is thoroughly exhausted. Meanwhile thebulb of the lamp may be heated in the known manner in order to depriveit of the occluded gases and vapours. The conduit 1 may also beconnected first to a so-called preliminary vacuum and then to a highvacuum pump. After a sufliciently high vacuum pump. After a suflicientlyhigh vacuum has been obtained in the lamp the conduit 1 is shut off fromthe vacuum pump or conduit and the lamp 14 is sealed in any suitablemanner, at a short distance above the collar 6, whereupon the pipe 25 isshut off from the compressed air supply by means of the valve 29.Preferably also the pipe 25 is then put into connection with a vacuumpipe, by means of the valve'29 and the pipe 31, for example with theso-called preliminary vacuum-pipe in which a pressure of for examplesome centimeters of mercury prevails and which is'commonly used inincandescent lamp manufacture.

Because of the shutting off of the compressed air the rubber tube 4returns into its primary or expanded position, which movement isfacilitated by producing a vacuum in the pipe 25. The exhaust tube 28 isthus disengaged from the rubber tube and as the whole weight of the lampno longer rests on the upper end of the rod 16 but only the weight ofthe stub or sealed oflf end of the exhaust tube, the latter is somewhatraised by reason of the spring 22, and thus acts to some extent as anejector of the exhaust tube so that its removal is facilitated.

As the rubber tube would reach an objec- A tionably high temperatureowing to the sealing-ofit' of the lamp, it is preferable that somecooling medium should be provided. To this end an annular cooling jacket12 is provided on the ring 13 which is mounted on the collar 6. Thejacket 12 is provided with inlet and outlet ipes 26 and 27 (Figure 2) tosome suitab e cooling-liquid.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. An exhaust head for engaging an exhaust tube and comprising a rigidtubular casing, a resilient tube mounted inside and concentric with saidcasing and joined air-tight at its ends to said casing, means forintroducing a fluid under pressure into the space between said casingand said tube, and a yielding support mounted in the bore of said casingand normally in position to be encountered by the inner end of anexhaust tube placed in said head, said support being resiliently held innormal osition and mounted to be moved longitudmallyof said casing andout of normal position by an exhaust tube inserted in said tube.

2. An exhaust head for engaging an exhaust tube and comprising a rigidtubular casing, a resilient tube mounted inside and concentric with saidcasing and joined air tight at its ends to said casing, means forintroducing a fluid under pressure into the space between said casingand said tube, and a yielding support mounted in the bore of said casingin position to be encountered by the inner end of an exhaust tube placedin said head,

said support comprising a rod mounted to move longitudinally of saidcasing, a head on said rod extending transversely of said casing toengage the inner end of an exhaust tube inserted in said tube, and acoil spring surrounding said rod to hold it in normal position andcompressed by movement of said rod due to insertion of an exhaust tubeinto said exhaust head.

3. An exhaust head for engaging an exhaust tube and comprising a rigidtubular casing, a resilient tube mounted inside and concentric with saidcasing and joined air tight at its ends to said'acasing, a resilientejector comprising a support and a spring connected thereto mounted insaid casing in posi- CERTIFICATE OF CORRECTION.

Patent No. l, 728, 034.

Granted September 10, 1929, to

IGOIRNELIS BOL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows:

Page 1, strike out line 12, and insert instead "atboth ends and meansforpressiug"; page 2, lines 50 and 51, strike out the words "After asufficiently high vacuum pump. and that j the said Letters Patent shouldbe read with these corrections therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 15th day of October, A. D. 1929.

! (Seal) M. J. Moore,- Acting Commissioner of Patents..

